Adjustable fluid pressure operated electric switch



Se t. 20, 1966 c. FRENDOCK 3,274,362

ADJUSTABLE FLUID PRESSURE OPERATED ELECTRIC SWITCH Filed July 15, 1964 5 Sheets-Sheen 1 INVENTOR CHARLES FRENDOCK Sept. 20, 1966 c. FRENDOCK 3,274,362

ADJUSTABLE FLUID PRESSURE OPERATED ELECTRIC SWITCH Filed July 15, 1964 a Sheets-Sheet 7| 73 65 68 11". II r/ A. ,1 F I llb INVENTOR CHARLES FRENDODK Fig.4 BY

ATT' RNEY Sept. 20, 1966 c. FRENDOCK ADJUSTABLE FLUID PRESSURE OPERATED ELECTRIC SWITCH Filed July 15, 1964 .3 Sheets-Sheet 3 INVENTOR a M: &

HEEZIUVM I United States Patent 3,274,362 ADJUSTABLE FLUID PRESSURE OPERATED ELECTRIC SWITCH Charles Frendock, Red Bank, N.J., assignor to The Wilcolator Company, Elizabeth, N..I., a corporation of Delaware Filed July 15, 1964, Ser. No. 382,799 4 Claims. (Cl. 200-140) This invention relates to condition responsive electric switches and more particularly to improvements in condition responsive switches of the slow make and break type which may be used to thermostatically control temperatures within close limits.

It is one object of this invention to provide an improved switch operable by thermal expansion of liquid and which is manually adjustable with precision within a predetermined temperature range, is readily calibrated, rugged and compact, and yet is inexpensive to manufacture.

Another object of this invention is the provision of an improved switch construction including a manually rotatable oontrol member or shaft for varying the response characteristics of the switch and having an off position in which the switch contacts are held open irrespective of temperatures experienced, and comprising novel drag brake and detent means for preventing inadvertent rotation of the control shaft from a desired setting and for providing tactile indication of the off position thereof.

It is another object of this invention to provide a switch of the foregoing character wherein the control shaft extends through a wall of switch housing means, such as a cover member thereof, and the brake and detent means comprises a washer mounted on the control shaft for rotation therewith and resilient biasing means such as a pair of spaced spring arms urging the washer into frictional engagement with a surface of the cover member to provide a drag 'brake action, the biasing means having a projection cooperable with a recess in the washer to provide tactile detent action when the control shaft is in its switch off position.

As another object this invention aims to provide an improved and particularly compact condition responsive switch construction comprising a housing having a switch in one side, a circular wafer-like expansible power element in the housing for operating the switch in response to condition changes, a manually rotatable control shaft and related structure on the wall of the housing opposite the side on which the switch is located, and a reciprocable member slideably mounted in the switch housing and operable to open the switch contacts upon rotation of the control shaft to an off position irrespective of operative conditions of the power element, the recipr0ca ble member in its preferred form comprising a generally rectangular slide having opposite sides slideable in grooves in opposite sides of the housing and having a window accommodating a portion of the expansible power element.

' Yet another object of the invention is the provision of an improved condition responsive switch of the foregoing character wherein the housing comprises a generally rectangular hollow insulating body having a bottom wall supporting a movable contact arm extending parallel to the bottom wall and disposed between laterally spaced shelves extending inwardly from opposite side walls of the housing body, the shelves supporting one end of a compression spring which acts against a wafer-like, contact arm operating expansible power element adjustably mounted on the inner end of a control shaft which is threadedly supported in a cover member closing the side of the housing opposite the bottom wall, the housing body further comprising opposed grooves in the side walls,

which grooves guide the edges of a rectangular slide member movable by cam means associated with the control shaft against the contact arm to effect opening of the switch contacts when the shaft is rotated to its off position, and one of the shelves having a well therein containing a hairpin-like spring one leg of which urges the slide member away from the contact arm.

The invention may be further said to reside in certain constructions and arrangements of parts by which the; foregoing objects and advantages, as well as others are achieved as will become apparent from the following detailed description of a switch embodying the invention.

In the accompanying sheets of drawings forming a part of this specification:

FIG. 1 is a side elevational view of a switch mechanism embodying the invention;

FIG. 2 is a plan view of the switch mechanism;

FIG. 3 is a sectional view, on an enlarged scale, taken substantially along line 3-3 of FIG. 2;

FIG. 4 is a sectional view taken along line 4-4 of FIG. 3;

FIG. 5 is a sectional view taken along line 55 of FIG. 1;

FIG. 6 is a view similar to FIG. 5 but showing parts in different operative positions;

FIG. 7 is an enlarged fragmentary sectional view taken along line 77 of FIG. 6; and

FIG. 8 is an exploded perspective view of the switch.

In the form of the invention illustrated in the drawings and described hereinafter there is provided a thermal condition responsive switch 10 comprising housing means including a generally rectangular, hollow housing body 11 which is formed of a suitable rigid insulating material such as molded Bakelite. The housing body 11 includes what will be referred to as side walls 11a and 11b, end walls and 11d, and a bottom wall He, although it will be understood that the switch 10 requires no particular orientation in use. The side of the housing body 11 opposite bottom wall He is closed by a metal wall or cover 12 which is secured to the housing body by screws 13 with a rectangular frame 15a of a spring metal brake and detent member 15 clamped between the cover and the housing body as illustrated in FIG. 3. The structure and purpose of the brake and detent member 15 will be later described in further detail.

A first conductor mmeber 20, formed of copper or the like, has a U-shaped portion including leg 20a extending through end wall 11c and overlying the inner surface of the bottom wall He. Conductor member 20 has another leg 20b recessed into the outer surface of bottom wall He and has its end formed into a blade type terminal 200. The legs 20a, 2012 are secured to the bottom wall 112 as by a rivet 21, with one end 22a of a movable contact arm 22 clamped between the leg 20a and the inner surface of the bottom wall He.

The contact arm 22 is formed of a resiliently flexible conductive material such as beryllium copper and is provided with stiffening flanges 23 extending from the free end 22b thereof toward the fixed end 22a but terminating shont of the conductor leg 20a so as to confine flexing of the contact arm to the area 22c adjacent the conductor leg 20a. The free end 22b of the contact arm 22 carries a movable contact 25 in the form of a short length of silver wire soldered to the contact arm transversely of its length. The movable contact 25 is cooperable with a fixed contact 26 in the form of a short length of silver wire soldered to one leg 28a of a second conductor member 28. The second conductor member 28 includes a leg 28b recessed into the outside surface of the bottom wall He and having its end formed into a blade type terminal 28c. The legs 28a and 28b are secured to the bottom wall He as by a suitable rivet 29.

See

The inherent resiliency of contact arm 22 normally holds the contact 25 closed against the contact 26, and is movable to effect opening of the contacts by a waferlike expansible power element generally indicated at 30. The expansible power element 30 comprises a pair of nested, cup-shaped metallic diaphragm members 32 and 33 which are welded about the periphery 34 thereof to define an expansible chamber therebetween. A metal ring 35 is secured to the diaphragm member 33 and has staked in the central opening thereof a post 36 for transmitting motions of the diaphragm member 33 to the contact arm 22, the post 36 being formed of a suitable rigid insulating material. The ring 35 presents an annular seat 38 which receives the smaller end of a conical compression spring 39, the larger end of which is seated on two laterally spaced shelves 40 and 41 extending inwardly from the housing side walls 11a and 11b, respectively.

.The spring 39 provides a predetermined load resisting expansion of the power element 30.

The expansible power element 30 is supported by a metal base 45 which is welded r brazed to the diaphragm member 32 and includes an axially extending support post 45a. The post 45a is slidably received in an axial bore 46 of a rotatable control shaft 47. This control shaft 47 is threadedly received in an internally threaded sleeve 48, which is conveniently formed integrally with cover 12, so that rotation of the control shaft will effect axial movement thereof with respect to the housing means. The end of the post 45a engages a ball type thrust bearing 50 in the bore 46 which opposes the force of load spring 39 and is adjustably positioned within the bore by a range adjusting screw 51 in the control shaft 47. The adjusting screw 51 provides for ready calibration of the switch in a manner described hereinafter.

The base member 45 is provided with an axial bore 56 in registration with an opening 57 through diaphragm member 32 in the interior of expansible power element 30. A radially extending passage 58 in base member 45 intersects bore 56 and receives one end 60a of a flexible capillary tube 60. The capillary tube 60 is provided with a plurality of helical coils 60b surrounding the base member 45 and is then led to the exterior of the housing body 11 through a notch 61 in end wall 110. The helical coils 60b accommodate movements of the expansible power element 30 within the housing means without exceeding the elastic limits of the tube 60.

The outer end of the capillary tube 60 terminates in a bulb 62 to form a closed system with the expansible power element 30. The bulb 62, capillary tube 60, and the power element 30 are filled with a suitable liquid which expands and contracts with increases and decreases in temperature. Upon increases in temperature and expansion of the liquid fill, the diaphragm member 33 and post 36 of the power element 30 will be moved away from diaphragm member 32 against the force of load spring 39 and, at a predetermined temperature, the post 36 will engage and move contact arm 22 to effect opening of the contacts 25 and 26. This temperature may be varied, within a predetermined range, by rotation of the control shaft 47 in the threaded sleeve 48 to advance or retract the power element 30 and post 36 with respect to the contact arm 22.

Means are provided to limit the extent of rotation of the control shaft 47, the limiting means comprising a washer 65 surrounding the inner end of the control shaft and slideably keyed or splined thereto by projections 65a extending into axially extending slots 66 of the shaft 47. The washer 65 is provided with a radially extending lug 68 which is engageable with a stop member 69 lanced downwardly from the cover 12, the engagement of the lug therewith serving to limit the rotation of the control shaft 47 to something less than one full revolution.

The washer 65 also forms part of the brake and detent means for preventing inadvertent rotation of the control shaft 47 from a desired setting and for providing a tactile indication of the off position thereof. To these ends the previously mentioned brake and detent member 15 comprises two spaced spring arms 70 and 71 extending inwardly of the rectangular frame 15a. The arms 70, 71 best illustrated in FIGS. 5 and 6, bear against the underside of the washer 65, urging it into frictional engagement with the inner surface of the cover 12 to serve as a drag brake against inadvertent rotation of the control shaft 47.

The free end of the spring arm 71 is provided with a ridge 73 which is engageable with a radial slot 74 in the washer 65 when the washer is in the position illustrated in FIG. 6 with the lug 68 thereof in engagement with one side of the stop member 69. The ridge 73 and slot 74 thereby cooperate to provide a tactile or sensible detent action when the shaft 47 is rotated to actuate the switch 10 to or from its off condition as described hereinafter.

It will be noted from FIGS. 5 and 6 that the spring arm 70 is provided with sufiicient area engaging the washer 65 to bridge the radial slot 74 therein so that the arm 70 has no detent action on the shaft 47 The switch 10 comprises means including a reciprocable slide member to hold the contacts 25, 26 open, irrespective of temperatures sensed by the bulb 62, when the shaft 47 is rotated clockwise as viewed in FIG. 2 to the off position in which lug 68 abuts stop 69 as shown in FIG. 6. The slide member 80, which is generally rectangular in shape, may be formed of a suitable rigid insulating material such as resin bonded fiber, and includes spaced parallel side bars 81, 82 joined by spaced parallel cross bars 83, 84 to define a rectangular window 85. The side bars 81 and 82 are slidably received in grooves 87 and 88 which are formed in the housing body 11 and guide the slide member 80 for reciprocable motion toward and away from the contact arm 22. The slide member 80 is normally biased away from the contact arm 22 by a hairpin shaped wire spring 90 which is confined in a well 91 formed in the spring supporting shelf 41 of the housing body 11. The spring 90 has one leg 90a resting on the bottom surface of the well 91 and its other leg 90b engaged in a notch 92 formed in cross bar 84 of the slide member 80.

The cross bar 83 of the slide member 80 is provided with an upward projection 94 having a sloping cam surface 95. Rotation of the control shaft 47 to its off position brings a beveled edge 68a of lug 68 into cooperating engagement with the sloping surface 95 so as to drive the slide member 80 downwardly against the action of spring 90, thereby bringing cross bar 84 into moving engagement with contact arm 22 and effecting opening of contacts 25, 26. In this position, the control shaft 47 is releasably held by the detent ridge 73 of arm 71 in engagement with slot 74 of the washer 65. Upon rotation of the control shaft 47 from its off position to a selected on position bar 84 is released by lug 68 and the spring 90 moves the slide member 80 away from contact arm 22 thereby allowing contacts 25, 26 to close, assuming of course that the temperature sensed by the bulb 62 is below the opening temperature selected by positioning the control shaft 47.

It will be noted from FIG. 3 that the window 85 of slide member 80 accommodates a portion of the expansible power element 30, thereby allowing a particularly compact construction, an important feature in the present day concern for reduction in size of control devices.

The switch 10 may be calibrated by setting the control shaft 47 at its limit of rotation away from the off position, subjecting the bulb 62 to the temperature at which it is desired the contacts will open with the control shaft so positioned, and then adjusting screw 51 until the contacts just open. Of course, the cooperating threads between the control shaft 47 and the sleeve 48 may be made either right-hand or left-hand as desired to provide a control switch 10 the contacts of which open upon either increasing or decreasing temperatures as the control shaft 47 is moved from its off position.

From the foreging detailed description of a control switch embodying the invention it will be recognized that there has been provided thereby a compact yet versatile and easily calibrated, manually adjustable condition responsive control switch, which by reason of its novel construction and arrangement of parts fulfills the objects and advantages previously set forth as well as others apparent from the foregoing description.

Although the present invention has been described in considerable detail with reference to a specific switch embodying the invention, it will be understood that the invention is not limited thereto, but rather the invention includes all those modifications, adaptations, substitutions, and uses as are reasonably embraced by the scope of the claims hereof.

Having described my invention, I claim:

1. A condition responsive switch comprising:

(a) housing means including a hollow body and a cover secured thereto,

(b) contact means in said housing means,

(c) condition responsive expansible power means in said housing means for operating said contact means in response to predetermined condition changes,

(d) a control shaft extending through said cover and rotatable to vary contact operating response of said power means to said predetermined condition changes,

(e) a washer mounted on said shaft by a splined connection for axial movement and rotation therewith, said washer having a aperture in one face thereof,

(f) biasing means comprising a pair of spring arrns each supported at one end and extending on opposite sides of said shaft and engaging said one surface of said washer for urging said washer into engagement with said cover for frictionally opposing rotation of said shaft, and

(g) one of said spring arms having a raised part engaging said washer and adapted to at least partially enter said aperture when said washer is rotated to bring said aperture into registration with said raised part to provide tactile indication of at least one rotative position of said shaft.

2. A condition responsive switch comprising:

(a) housing means including a hollow rectangular body of electrically insulating material having a bottom wall, side walls, and a cover member closing the side of said hollow body opposite said bottom wall,

(b) a movable contact arm extending parallel to said bottom wall, said arm normally biasing a movable contact into a closed position with respect to a fixed contact,

(c) an expansible power element operative to move said arm to open said contacts in response to a predetermined condition,

(d) control means rotatably mounted on said cover member and operable to adjust the position of said power element with respect to said arm for selecting said predetermined condition,

(e) a pair of shelves extending inwardly from opposite side walls and defining a space therebetween in which said contact arm is disposed, said shelves supporting one end of a compression load spring the other end of which acts against said power element,

(f) said side walls having a pair of opposed grooves formed therein, said grooves extending normal to said bottom wall,

(g) a rectangular slide member having its side edges slideably received in said grooves,

(h) one of said shelves having a well therein containing a hairpin-like spring one leg of which urges said slide member in a direction away from said contact arm, and

(i) said slide member being movable against said contact arm to effect opening of said contacts by rotation of said control means to a predetermined position.

3. A condition responsive switch as defined in claim 1 further characterized by the other of said arms having a part engaging said one surface of said washer over an area so as to bridge said aperture and remain engaged with said one surface when said washer is rotated to bring said aperture into registration with said part of said other arm.

4. A condition responsive switch comprising:

(a) housing means including a hollow body and a cover,

(b) contact means in said housing means,

(c) an expansible power element in said housing means and comprising a support post and circular wafer-like diaphragm means movable toward and away from said support post to operate said contact means in response to predetermined condition changes,

(d) load spring means urging said power element toward said cover,

(e) a control shaft threadedly mounted with respect to said cover for axial movement upon rotation of said shaft, said control shaft having an axial bore receiving said support post whereby said power element is positionable to select said predetermined condition by rotation of said shaft,

(f) a member slideably mounted on said shaft for rotation therewith,

(g) detent means cooperable with said member to porvide tactile indication of at least one rotative position of said shaft,

(h) biasing means urging said member into frictional engagement with said cover for retarding rotation of said shaft, and

(i) a reciprocable element mounted in said housing means and biased in one direction by spring means and movable in the opposite direction to effect opening of said contacts, said member on said control shaft being cooperable with said element to effect movement thereof in said opposite direction to open said contacts upon rotation of said shaft to said one position, said reciprocable element having a window receiving a portion of said diaphragm means.

References Cited by the Examiner UNITED STATES PATENTS 6 BERNARD A. GILHEANY, Primary Examiner.

G. MAIER, Assistant Examiner. 

1. A CONDITION RESPONSIVE SWITCH COMPRISING: (A) HOUSING MEANS INCLUDING A HOLLOW BODY AND A COVER SECURED THERETO, (B) CONTACT MEANS IN SAID HOUSING MEANS, (C) CONDITION RESPONSIVE EXPANSIBLE POWER MEANS IN SAID HOUSING MEANS FOR OPERATING SAID CONTACT MEANS IN RESPONSE TO PREDETERMINED CONDITION CHANGES, (D) A CONTROL SHAFT EXTENDING THROUGH SAID COVER AND ROTATABLE TO VARY CONTACT OPERATING RESPONSE OF SAID POWER MEANS TO SAID PREDETERMINED CONDITION CHANGES, (E) A WASHER MOUNTED ON SAID SHAFT BY A SPLINED CONNECTION FOR AXIAL MOVEMENT AND ROTATION THEREWITH, SAID WASHER HAVING A APERTURED IN ONE FACE THEREOF, (F) BIASING MEANS COMPRISING A PAIR OF SPRING ARMS EACH SUPPORTED AT ONE END AND EXTENDING ON OPPOSITE SIDES OF SAID SHAFT AND ENGAGING SAID ONE SURFACE OF SAID WASHER FOR URGING SAID WASHER INTO ENGAGEMENT WITH SAID COVER FOR FRICTIONALLY OPPOSING ROTATION OF SAID SHAFT, AND (G) ONE OF SAID SPRING ARMS HAVING A RAISED PART ENGAGING SAID WASHER AND ADAPTED TO AT LEAST PARTIALLY ENTER SAID APERTURE WHEN SAID WASHER IS ROTATED TO BRING SAID APERTURE INTO REGISTRATION WITH SAID RAISED PART TO PROVIDE TACTILE INDICATION OF AT LEAST ONE ROTATIVE POSITION OF SAID SHAFT. 